I'm no techie and it used to happen to me. I thought that something was wrong. Not anymore, I drive my S everywhere almost every day. In my humble opinion I think it is all down to reaching a point where one is at one with the car. I drive nothing else now and am attuned to the S and its foibles, I have no mods on my car.

 

You know it makes sense

 

If it's happening on speed bumps and rough roads then it's simply your foot bouncing on the gas peddle. It used to happen to me all the time when I first go the car. Nothing to worry about. You'll get used to it. If in doubt just floor it!!

Lol

 

It's normal and it'll only happen when it's warm out and at slow sweeds.

A cold air intake may fix it, but may deteriorate performance under other driving conditions.

Sometimes it helps to declutch and rev the engine for a second so it can suck more fresh air.

-Marin